The Ganglioside Gm1 In Mammalian Sperm Function

GM1 is known to influence several signaling pathways in somatic cells that are also important in sperm functional maturation, such as “capacitation” and fertilization. These pathways include tyrosine phosphorylation and exocytosis of the acrosomal vesicle (AE). I report that the ganglioside GM1 is enriched in a stable, micron-scale sub-domain in the plasma membrane overlying the acrosome of the sperm head in several species. This membrane sub-domain is conserved across several mammalian species. The domain appears to be specifically masked by seminal vesicle fluid secretions during the process of insemination. I also report that the acrosomal vesicle membrane is enriched in GM1. This enrichment may act to increase plasma membrane GM1 during point-fusion events between the acrosomal and plasma membranes. I investigated the impact of modulating the GM1 concentrations in sperm membranes. I found that exogenous GM1 stimulated an increase in intracellular calcium and accelerated tyrosine phosphorylation cascades in sperm through activation of the TrkA kinase pathway, by-passing the need for sterol efflux in this pathway. Additionally, I found that changing GM1 focal enrichments in the plasma membrane, either through the addition of exogenous GM1 or using the pentameric B subunit of cholera toxin to cross-link endogenous GM1, induced AE. The effect of GM1 clustering appeared to be mediated by the sialic acid residue of GM1 because ceramide and asialo-GM1 were unable to induce such effects. GM1 influences many calcium dependent processes in other cell types, and I hypothesized that a similar calcium-dependent process was active in sperm. AE was inhibited in a concentration-dependent manner by inhibiting calcium channel activity either with Ni2+ or store-operated calcium channels and CaV2.3 calcium channel inhibitors. Sperm lacking the CaV2.3 channel displayed impaired fertility and were unable to undergo AE in response to progesterone, zona pellucida, or GM1, despite apparently normal capacitation and membrane fusion. Together, these data suggest a model in which an increase in plasma membrane fluidity during sterol efflux, together with point fusions between the plasma membrane and acrosomal membrane, allow the clustering of endogenous GM1. This clustering then stimulates calcium influx through the CaV2.3 channel and signaling pathways necessary for mammalian fertilization

\u3ci\u3eEchinococcus\u3c/i\u3e spp. Tapeworms in North America

Alveolar and cystic echinococcosis are emerging and re-emerging in Europe, Africa, and Asia. The expansion of Echinococcus spp. tapeworms in wildlife host reservoirs appears to be driving this emergence in some areas. Recent studies suggest a similar phenomenon may be occurring in North America. We describe the context of Echinococcus spp. research in North America, with a specific focus on the contiguous United States. Although studies were conducted in the United States throughout the 1900s on various sylvatic and domestic Echinococcus spp. tapeworm cycles, data are lacking for the past ≈30 years. We review previous research, provide analysis of more recent focal studies, and suggest that Echinococcus spp. tapeworms, in particular E. canadensis, may be underrecognized. As a result, we suggest that additional research and surveillance be conducted for these tapeworms in wildlife host reservoirs across the United States

Risk-enhancing behaviors associated with human injuries from bison encounters at Yellowstone National Park, 2000–2015

Yellowstone National Park is home to the largest bison population on public land in the United States. Although Yellowstone regulations require visitors to remain at least 23 m from bison, since 1980, bison have injured more visitors to Yellowstone than any other animal. We examined a series of bison-related injuries at Yellowstone to evaluate the circumstances of these injuries and to identify common risk-enhancing behaviors that lead to injury. To do this, we analyzed narrative case incident records from law enforcement regarding bison-human encounters in Yellowstone during 2000–2015. Data regarding demographics, preencounter ac- tivities, number of persons involved, type of injury, and acknowledgement of appropriate viewing distance were extracted from the records. Bison encounters resulted in injury to 25 persons (21 visitors and 4 employees). Age range for injured persons was 7–68 years (median: 49 years), and 13 were female. All injuries occurred in areas of high visitor concentration. Mean visitor distance from bison before injury was 3.4 m (range: 0.3–6.1 m). Twenty persons (80%) actively approached bison before their injuries; 5 (20%) failed to retreat when bison approached. Fifteen persons (60%) were injured when in a group of ≥3 persons approaching bison. Twelve persons (48%) sustained injuries while photographing bison. Six persons (24%) acknowledged they were too close to bison. Education alone might not be sufficient to reduce bison-related injuries. Effective injury pre- vention campaigns for national parks require an understanding of the behaviors and motivations of persons who approach bison. Including behavioral science and behavior change techniques in bison injury prevention cam- paigns might reduce injuries at Yellowstone

Deer management generally reduces densities of nymphal Ixodes scapularis, but not prevalence of infection with Borrelia burgdorferi sensu stricto

Human Lyme disease–primarily caused by the bacterium Borrelia burgdorferi sensu stricto (s.s.) in North America–is the most common vector-borne disease in the United States. Research on risk mitigation strategies during the last three decades has emphasized methods to reduce densities of the primary vector in eastern North America, the blacklegged tick (Ixodes scapularis). Controlling white-tailed deer populations has been considered a potential method for reducing tick densities, as white-tailed deer are important hosts for blacklegged tick reproduction. However, the feasibility and efficacy of white-tailed deer management to impact acarological risk of encountering infected ticks (namely, density of host-seeking infected nymphs; DIN) is unclear. We investigated the effect of white-tailed deer density and management on the density of host-seeking nymphs and B. burgdorferi s.s. infection prevalence using surveillance data from eight national parks and park regions in the eastern United States from 2014–2022. We found that deer density was significantly positively correlated with the density of nymphs (nymph density increased by 49% with a 1 standard deviation increase in deer density) but was not strongly correlated with the prevalence of B. burgdorferi s.s. infection in nymphal ticks. Further, while white-tailed deer reduction efforts were followed by a decrease in the density of I. scapularis nymphs in parks, deer removal had variable effects on B. burgdorferi s.s. infection prevalence, with some parks experiencing slight declines and others slight increases in prevalence. Our findings suggest that managing white-tailed deer densities alone may not be effective in reducing DIN in all situations but may be a useful tool when implemented in integrated management regimes

A One Health message about bats increases intentions to follow public health guidance on bat rabies

Since 1960, bat rabies variants have become the greatest source of human rabies deaths in the United States. Improving rabies awareness and preventing human exposure to rabid bats remains a national public health priority today. Concurrently, conservation of bats and the ecosystem benefits they provide is of increasing importance due to declining populations of many bat species. This study used a visitor-intercept experiment (N = 521) in two U.S. national parks where human and bat interactions occur on an occasional basis to examine the relative persuasiveness of four messages differing in the provision of benefit and uncertainty information on intentions to adopt a rabies exposure prevention behavior. We found that acknowledging benefits of bats in a risk message led to greater intentions to adopt the recommended rabies exposure prevention behavior without unnecessarily stigmatizing bats. These results signify the importance of communicating benefits of bats in bat rabies prevention messages to benefit both human and wildlife health

Risk-enhancing behaviors associated with human injuries from bison encounters at Yellowstone National Park, 2000–2015

Yellowstone National Park is home to the largest bison population on public land in the United States. Although Yellowstone regulations require visitors to remain at least 23 m from bison, since 1980, bison have injured more visitors to Yellowstone than any other animal. We examined a series of bison-related injuries at Yellowstone to evaluate the circumstances of these injuries and to identify common risk-enhancing behaviors that lead to injury. To do this, we analyzed narrative case incident records from law enforcement regarding bison-human encounters in Yellowstone during 2000–2015. Data regarding demographics, preencounter ac- tivities, number of persons involved, type of injury, and acknowledgement of appropriate viewing distance were extracted from the records. Bison encounters resulted in injury to 25 persons (21 visitors and 4 employees). Age range for injured persons was 7–68 years (median: 49 years), and 13 were female. All injuries occurred in areas of high visitor concentration. Mean visitor distance from bison before injury was 3.4 m (range: 0.3–6.1 m). Twenty persons (80%) actively approached bison before their injuries; 5 (20%) failed to retreat when bison approached. Fifteen persons (60%) were injured when in a group of ≥3 persons approaching bison. Twelve persons (48%) sustained injuries while photographing bison. Six persons (24%) acknowledged they were too close to bison. Education alone might not be sufficient to reduce bison-related injuries. Effective injury pre- vention campaigns for national parks require an understanding of the behaviors and motivations of persons who approach bison. Including behavioral science and behavior change techniques in bison injury prevention cam- paigns might reduce injuries at Yellowstone

\u3ci\u3eEchinococcus\u3c/i\u3e spp. Tapeworms in North America

Alveolar and cystic echinococcosis are emerging and re-emerging in Europe, Africa, and Asia. The expansion of Echinococcus spp. tapeworms in wildlife host reservoirs appears to be driving this emergence in some areas. Recent studies suggest a similar phenomenon may be occurring in North America. We describe the context of Echinococcus spp. research in North America, with a specific focus on the contiguous United States. Although studies were conducted in the United States throughout the 1900s on various sylvatic and domestic Echinococcus spp. tapeworm cycles, data are lacking for the past ≈30 years. We review previous research, provide analysis of more recent focal studies, and suggest that Echinococcus spp. tapeworms, in particular E. canadensis, may be underrecognized. As a result, we suggest that additional research and surveillance be conducted for these tapeworms in wildlife host reservoirs across the United States

Rift Valley Fever: improving predictive models for disease forecasting

Rift Valley Fever (RVF) is an arthropod-borne disease endemic to much of Sub-Saharan Africa and the Arabian Peninsula causing abortion storms and high neonatal mortality in sheep, goats, and cattle and influenza-like to hemorrhagic illness in humans. RVF is transmitted by over 30 species of arthropods and can persist in the soil for decades in the trans-ovarially infected, desiccation resistant eggs of Aedine species of mosquitoes. Recent increases in the severity and frequency of RVF outbreaks within East Africa in addition to concern for the potential for RVF spread to new areas has prompted interest by several public health authorities in improving disease forecasting tools. This report describes factors of RVF ecology and epidemiology important to current disease forecasting efforts and gives recommendations for the spatial and temporal refinement of extant modelling efforts

Echinococcus spp. Tapeworms in North America

Alveolar and cystic echinococcosis are emerging and reemerging in Europe, Africa, and Asia. The expansion of Echinococcus spp. tapeworms in wildlife host reservoirs appears to be driving this emergence in some areas. Recent studies suggest a similar phenomenon may be occurring in North America. We describe the context of Echinococcus spp. research in North America, with a specific focus on the contiguous United States. Although studies were conducted in the United States throughout the 1900s on various sylvatic and domestic Echinococcus spp. tapeworm cycles, data are lacking for the past ≈30 years. We review previous research, provide analysis of more recent focal studies, and suggest that Echinococcus spp. tapeworms, in particular E. canadensis, may be underrecognized. As a result, we suggest that additional research and surveillance be conducted for these tapeworms in wildlife host reservoirs across the United States